Direct process for the production of cellulose esters

Abstract

The present invention relates to a process for preparing cellulose esters having a total DS/AGU of 0.1 to 3.0, said process comprising contacting the following: (i) a cellulose material, (ii) a solubilizing amount of a solvent system comprising a carboxamide diluent or a urea-based diluent, (iii) an acylating reagent, and (iv) a titanium-containing compound.

We claim: 
     
       1. A process for preparing cellulose esters having a total DS/AGU of 0.1 to 3.0, said process comprising contacting the following: (i) a cellulose material,   (ii) a solubilizing amount of a solvent system for said resultant cellulose esters comprising either a carboxamide diluent or a urea-based diluent, wherein the carboxamide portion of said carboxamide diluent comprises the structure: R 4  R 5  NCOCR 6  R 7  R 8 , wherein R 4 , R 5 , R 6 , R 7 , and R 8  are independently selected from the group consisting of hydrogen, alkyl having from about 1 to about 20 carbon atoms, branched alkyl having from about 1 to about 20 carbon atoms, phenyl, naphthyl, alkenyl having from about 1 to about 20 carbon atoms, and branched alkenyl having from about 1 to about 20 carbon atoms, and   wherein said urea portion of said urea-based diluent comprises the structure: R 9  R 10  NCONR 11  R 12 , wherein R 9 , R 10 , R 11 , and R 12  are independently selected from the group consisting of hydrogen, alkyl having from about 1 to about 20 carbon atoms, branched alkyl having from about 1 to about 20 carbon atoms, phenyl, naphthyl, alkenyl having from about 1 to about 20 carbon atoms, and branched alkenyl having from about 1 to about 20 carbon atoms,     (iii) an acylating reagent selected from the group consisting of (a) an acid chloride, and optionally, an acid acceptor,   (b) a carboxylic acid anhydride,   (c) any one of diketene, ketene, 2,2,6-trimethyl-4H-1,3-dioxin-4-one, and an ester of acetoacetic acid,   (d) an ester of a carboxylic acid, and combinations of one or more of (a)-(d), and     (iv) a titanium-containing compound; wherein said components (i) and (ii) are contacted first and components (iii) and (iv) are contacted with the product of said contacting of components (i) and (ii), in any order.     
     
     
       2. The process of claim 1, wherein after said contacting, the resultant esterified cellulose is a partially esterified cellulose having a total DS/AGU of less than 3.0 and the partially esterified cellulose is not hydrolysed during said contacting or in a subsequent step. 
     
     
       3. The process of claim 1, wherein the solvent system does not contain lithium chloride. 
     
     
       4. A process for preparing cellulose esters having a total DS/AGU of 0.1 to 3.0, said process comprising contacting the following: (i) a cellulose material,   (ii) a solubilizing amount of a solvent system for said resultant cellulose esters comprising a carboxamide diluent, wherein the carboxamide of said carboxamide diluent has the structure: R 4  R 5  NCOCR 6  R 7  R 8 , wherein R 4 , R 5 , R 6 , R 7  and R 8  are independently selected from the group consisting of hydrogen, alkyl having from about 1 to about 20 carbon atoms, branched alkyl having from about 1 to about 20 carbon atoms, phenyl, naphthyl, alkenyl having from about 1 to about 20 carbon atoms, and branched alkenyl having from about 1 to about 20 carbon atoms,     (iii) an acylating reagent selected from the group consisting of (a) an acid chloride, and optionally, an acid acceptor,   (b) a carboxylic acid anhydride,   (c) any of one of diketene, ketene, 2,2,6-trimethyl-4H-1,3-dioxin-4-one, an ester of acetoacetic acid,   (d) an ester of a carboxylic acid, and combinations of one or more of (a)-(d), and     (iv) a titanium-containing compound; wherein said components (i) and (ii) are contacted first and components (iii) and (iv) are contacted with the product of said contacting of components (i) and (ii), in any order.     
     
     
       5. The process of claim 4, wherein after said contacting, the resultant esterified cellulose is a partially esterified cellulose having a total DS/AGU of less than 3.0 and the partially esterified cellulose is not hydrolysed during said contacting or in a subsequent step. 
     
     
       6. The process of claim 4, wherein the solvent system does not contain lithium chloride. 
     
     
       7. The process of claim 4 wherein said cellulose esters comprise the structure: ##STR3## wherein R, R', and R'" are selected separately from the group consisting of: hydrogen, with the proviso that R, R', and R'" are not all hydrogen simultaneously; acetoacetyl; and R 1  C═O wherein R 1  is selected from the group consisting of: alkyl having from about 1 to about 30 carbons; carboxyalkyl of the structure (CH 2 ) m  CO 2  H, where M is from 2 to 6; carboxyalkenyl of the structure, CR 2  ═CR 3  CO 2  H, where R 2  and R 3  are independently selected from the group consisting of hydrogen, methyl, branched alkyl having from about 1 to about 30 carbons, phenyl, and naphthyl; alkenyl having from about 1 to about 30 carbon atoms and from one to three double bonds; and branched alkenyl having from about 1 to about 30 carbon atoms and having from one to three double bonds. 
     
     
       8. The process of claim 7 wherein said m of said carboxyalkyl is from 2 to 4. 
     
     
       9. The process of claim 7 wherein R, R', and R'" are independently selected from hydrogen, acetyl, propionyl and butyryl. 
     
     
       10. The process of claim 4 wherein the amount of cellulose material is about 1.0 percent to about 50 percent, based on the weight of said carboxamide, and the amount of said titanium-containing compound is about 0.1 percent to about 20 percent, based on the weight of said cellulose material. 
     
     
       11. The process of claim 4 wherein the amount of cellulose material is about 9 percent to about 28 percent, based on the weight of said carboxamide, and the amount of said titanium-containing compound is about 1.0 percent to about 10 percent, based on the weight of said cellulose material. 
     
     
       12. The process of claim 4 wherein the total DS/AGU of the cellulose ester is about 2.0 to about 3.0. 
     
     
       13. The process of claim 4 wherein the total DS/AGU of the cellulose ester is about 2.4 to about 2.9. 
     
     
       14. The process of claim 4 wherein said carboxamide diluent is selected from the group consisting of 1-methyl-2-pyrrolidinone, N,N-dimethylpropionamide, N,N-diethylacetamide and N,N-dimethylacetamide. 
     
     
       15. The process of claim 4 wherein said carboxamides are selected from the group consisting of succinimides, phthalimides and glutarimides. 
     
     
       16. The process of claim 4 wherein said ester of acetoacetic acid is tert-butyl acetoacetate. 
     
     
       17. The process of claim 4 wherein said carboxylic anhydride is selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, nonanoic anhydride, lauric anhydride, palmitic anhydride, and stearic anhydride. 
     
     
       18. The process of claim 4 wherein said esters of carboxylic acids are esters formed from the group consisting of the following acids: capric, lauric, palmitic, stearic, oleic, linoleic, linolenic, cyclohexanedicarboxylic, benzoic, substituted benzoic, phthalic, isophthalic and terephthalic. 
     
     
       19. The process of claim 4 wherein said acid chloride is selected from the group consisting of acetyl chloride, propionyl chloride, butyryl chloride, hexanoyl chloride, lauroyl chloride, stearoyl chloride. 
     
     
       20. The process of claim 4 wherein said acid acceptor is selected from the group consisting of pyridine, triethylamine, sodium bicarbonate and sodium acetate. 
     
     
       21. The process of claim 4 wherein said acid acceptor is pyridine. 
     
     
       22. The process of claim 4 wherein said titanium-containing compounds are titanium (IV) compounds selected from the group consisting of titanic acid, titanate esters, tetra(amino)titanium compounds or mixtures thereof. 
     
     
       23. The process of claim 4 wherein said titanium-containing compounds are selected from the group consisting of tetra(2-propyl)titanate, titanic acid, tetra(1-propyl)titanate, tetra(1-butyl)titanate, and tetrakis(dimethylamino)titanium. 
     
     
       24. The process of claim 4 wherein said cellulose material is selected from the group consisting of hardwood pulp, softwood pulp, cotton linters, bacterial cellulose, and regenerated cellulose. 
     
     
       25. The process of claim 4 carried out at a temperature between about 0° C. and about 200° C. 
     
     
       26. The process of claim 4 carried out at a temperature between about 100° C. and about 180° C. 
     
     
       27. The process of claim 4 carried out at a temperature between about 120° C. and about 170° C. 
     
     
       28. The process of claim 4 including the additional step of insolubilizing the cellulose ester by addition of an insolubilizing amount of a nonsolvent. 
     
     
       29. The process of claim 28 further comprises separating the insolubilized cellulose ester. 
     
     
       30. The process of claim 29 wherein said nonsolvent is methanol, ethanol, propanol, water, or a mixture thereof. 
     
     
       31. A process for preparing cellulose esters having a total DS/AGU of 0.1 to 3.0, said process comprising contacting the following: (i) a cellulose material,   (ii) a solubilizing amount of a solvent system for said resultant cellulose esters comprising a urea-based diluent, wherein said urea-based compound of said urea-based diluent has the structure: R 9  R 10  NCONR 11  R 12 , wherein R 9 , R 10 , R 11 , and R 12  are independently selected from the group consisting of hydrogen, alkyl having from about 1 to about 20 carbon atoms, branched alkyl having from about 1 to about 20 carbon atoms, phenyl, naphthyl, alkenyl having from about 1 to about 20 carbon atoms, and branched alkenyl having from about 1 to about 20 carbon atoms,     (iii) an acylating reagent selected from the group consisting of (a) an acid chloride, and optionally, an acid acceptor,   (b) a carboxylic acid anhydride,   (c) any one of diketene, ketene, 2,2,6-trimethyl-4H-1,3-dioxin-4-one, and an ester of acetoacetic acid,   (d) an ester of a carboxylic acid, and combinations of one or more of (a)-(d), and     (iv) a titanium-containing compound; wherein said components (i) and (ii) are contacted first and components (iii) and (iv) are contacted with the product of said contacting of components (i) and (ii), in any order.     
     
     
       32. The process of claim 31, wherein after said contacting, the resultant esterified cellulose is a partially esterified cellulose having a total DS/AGU of less than 3.0 and the partially esterified cellulose is not hydrolysed during said contacting or in a subsequent step. 
     
     
       33. The process of claim 31, wherein the solvent system does not contain lithium chloride. 
     
     
       34. The method of claim 31 wherein said cellulose esters comprise the structure: ##STR4## wherein R, R', and R'" are selected separately from the group consisting of: hydrogen, with the proviso that R, R', and R'" are not all hydrogen simultaneously; acetoacetyl; and R 1  C═O wherein R 1  is selected from the group consisting of alkyl having from about 1 to about 30 carbons; carboxyalkyl of the structure (CH 2 ) m  CO 2  H, where m is from about 2 to 6; carboxyalkenyl of the structure CR 2  ═CR 3  CO 2  H, where R 2  and R 3  are independently selected from the group consisting of hydrogen or methyl, branched alkyl having from about 1 to about 30 carbons, phenyl and naphthyl; alkenyl having from about 1 to about 30 carbon atoms and having from one to three double bonds; and branched alkenyl having from about 1 to about 30 carbon atoms and having from one to three double bonds. 
     
     
       35. The process of claim 34 wherein said m of said carboxyalkyl is from 2 to 4. 
     
     
       36. The process of claim 34 wherein one of R 9  and R 10  and one of R 11  and R 12  are connected to form a cyclic urea. 
     
     
       37. The process of claim 35 wherein R, R', and R'" are independently selected from hydrogen, acetyl, propionyl and butyryl. 
     
     
       38. The process of claim 34 wherein the amount of cellulose material is about 1.0 percent to about 50 percent, based on the weight of said urea-based compound, and the amount of said titanium-containing compound is about 0.1 percent to about 20 percent, based on the weight of said cellulose material. 
     
     
       39. The process of claim 34 wherein the amount of cellulose material is about 9 percent to about 28 percent, based on the weight of said urea-based compound, and the amount of said titanium-containing compound is about 1.0 percent to about 10 percent, based on the weight of said cellulose material. 
     
     
       40. The process of claim 34 wherein the total DS/AGU of the cellulose ester is about 2.0 to about 3.0. 
     
     
       41. The process of claim 34 wherein the total DS/AGU of the cellulose ester is about 2.4 to about 2.9. 
     
     
       42. The process of claim 34 wherein said urea-based compound is selected from the group consisting of urea and N,N-dimethylimidazolidinone. 
     
     
       43. The process of claim 34 wherein said ester of acetoacetic acid is tert-butyl acetoacetate. 
     
     
       44. The process of claim 34 wherein said carboxylic anhydride is selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, nonanoic, lauric, palmitic, and stearic. 
     
     
       45. The process of claim 34 wherein said esters of carboxylic acids are selected from the group consisting of the following acids: capric, lauric, palmitic, stearic, oleic, linoleic, linolenic, cyclohexanedicarboxylic, benzoic, substituted benzoic, phthalic, isophthalic and terephthalic. 
     
     
       46. The process of claim 34 wherein said acid chloride is selected from the group consisting of acetyl chloride, propionyl chloride, butyryl chloride, hexanoyl chloride, lauroyl chloride and stearoyl chloride. 
     
     
       47. The process of claim 34 wherein said acid acceptor is selected from the group consisting of pyridine, triethylamine, sodium bicarbonate and sodium acetate. 
     
     
       48. The process of claim 34 wherein said acid acceptor is pyridine. 
     
     
       49. The process of claim 34 wherein said titanium-containing compounds are titanium (IV) compounds selected from the group consisting of titanic acid, titanate esters, tetra(amino)titanium compounds or mixtures thereof. 
     
     
       50. The process of claim 34 wherein said titanium-containing compounds are selected from the group consisting of tetra(2-propyl)titanate, titanic acid, tetra(1-propyl)titanate, tetra(1-butyl)titanate, and tetrakis(dimethylamino)titanium. 
     
     
       51. The process of claim 34 wherein said cellulose material is selected from the group consisting of hardwood pulp, softwood pulp, cotton linters, bacterial cellulose, and regenerated cellulose. 
     
     
       52. The process of claim 34 carried out at a temperature between about 0° C. and about 200° C. 
     
     
       53. The process of claim 34 carried out at a temperature between about 100° C. and about 180° C. 
     
     
       54. The process of claim 34 carried out at a temperature between about 120° C. and about 170° C. 
     
     
       55. The process of claim 34 including the additional step of insolubilizing the cellulose ester by addition of an insolubilizing amount of a nonsolvent. 
     
     
       56. The process of claim 55 further comprising separating the insolubilized cellulose ester. 
     
     
       57. The process of claim 55 wherein said nonsolvent is methanol, ethanol, propanol, water, or a mixture thereof.